"String cannot be converted to PubliclyCloneable" Java Issue -

so trying add few strings doubly linked list keep getting error string cannot converted publiclycloneable (an interface extends cloneable, use purposes of creating clone() , copy constructor, la textbook's explanation). here demo code looks like:

public static void main(string[] args)  {     doublylinkedlist list1 = new doublylinkedlist();     doublylinkedlist.doublylinkediterator = list1.iterator();      string pittsburgh1 = new string("penguins");     string pittsburgh2 = new string("pirates");     string pittsburgh3 = new string("steelers");      list1.addtostart(pittsburgh1);     list1.addtostart(pittsburgh2);     list1.addtostart(pittsburgh3);      system.out.println("list contains:");     i.restart();     while (i.hasnext())         system.out.println(i.next());     system.out.println(""); 

here beginning part of class doublylinkedlist:

public class doublylinkedlist<t extends publiclycloneable> implements publiclycloneable { private class twowaynode<t> {     private t data;     private twowaynode<t> next;     private twowaynode<t> prev;      public twowaynode()     {         data = null;         next = null;         prev = null;     }      public twowaynode(t newdata, twowaynode<t> prevnode, twowaynode<t> nextnode)     {         data = newdata;         next = nextnode;         prev = prevnode;     } } 

here method causing compiler error:

public void addtostart(t itemdata) {     twowaynode<t> newhead = new twowaynode(itemdata, null, head);     if (head != null)     {         head.prev = newhead;     }     head = newhead; } 

and here interface using:

public interface publiclycloneable extends cloneable { public object clone(); } 

so there overlooking here, trying accomplish possible? there sort of typecast or type assignment can add 3 strings list?

your addtostart method accepts argument of type t, t defined class t extends publiclycloneable.

since java.lang.string not implement publiclycloneable, cannot argument type doublylinkedlist. if want main function test class, i'd implement simple-stupid publiclyclonablestring class::

public class publiclyclonablestring implements publiclyclonable {     private string s;     public publiclyclonablestring (string s) {         this.s = s;     }      @override     public string clone() {         return s; // ok, since strings immutable     }      // getter, setter, etc. }